This invention relates in general to a railroad distributed power communication system for controlling the functionality of one or more transceiver units on the locomotives or railcars of a train remote from a lead transceiver unit on a lead locomotive and more specifically to a method and system for verifying that one or more remote transceiver units have received and are responsive to a command message from the lead locomotive.
Communication among mobile assets, such as locomotives and other cars in a train consist, is important to ensure the coordination of various functions of the mobile assets. Functions such as throttle control, braking and direction, for example, are important to coordinate among locomotives during a train consist's operation. Radio frequency schemes may be used for intra-train communication within the consist with various combinations of transmitters, receivers and/or transceivers being distributed among the lead and remote locomotives. During a locomotive distributed power operation the lead or command locomotive may transmit instructions or control information in a command message to one or more remote or controlled locomotives that are located in the back of or behind the lead locomotive within a train consist. On receipt of the command message, the remote locomotives may transmit a reply message to the lead locomotive including the remote locomotives actual status information pertaining to the command message instructions. If the lead locomotive is satisfied that it has received a reply message from all of the remote locomotives then the lead locomotive may declare that all remotes are following the command message instructions. Alternatively, if the lead locomotive does not receive a reply message from each remote locomotive within a certain period of time then the lead locomotive may assume that communication has been lost and that one or more of the remote locomotives is not following the command message instructions. However, the lead locomotive not receiving a status reply message from one or more remote locomotives does not necessarily mean that those locomotives are not following the command message instruction.
For example, locomotive consists traverse a wide range of topographies including mountainous terrain and other areas having physical features, such as tunnels, that may cause a loss of communication among locomotives in the consist. When traveling through such areas the lead locomotive's operator may interpret the lack of a status reply message from a remote locomotive to mean that the remote locomotive did not receive the proper command message information. However, the lead locomotive may not have received the remote locomotive's status reply message because it was lost due to a communication breakdown between the lead locomotive and the remote locomotive. In this respect, the remote locomotive may be following the command message instructions while the operator of the lead locomotive erroneously concludes that the remote locomotive is not following the command message instructions. This situation may cause the operator to take corrective action that could be avoided if the operator knew the remote locomotive was following the command message instructions. Rapid verification that remote locomotives have received a command message and are following command instructions allows for improved operating efficiency of the train consist.
In view of the above, it would advantageous to provide a method and system for verifying that a remote locomotive, or locomotives, is following a set of command message instructions even though the lead locomotive is out of direct communication with the remote locomotive.